Hydraulic press system with control means yielding high-speed operation thereof



Sept. 21, 1948. E. CANNON 2,449,639

HYDRAULIC PRESS, SYSTEM WITH CONTROL MEANS YIELDING HIGH-SPEED OPERATION THEREOF Fild Jan. 15, 1943 3 Sheets-Sheet l INVENTOR 19431 CMI/o/a/ E. CAN NON, HYDRAULIC PRESS SYSTEM WITH CONTROL MEANS Sept. 21, 1948.

YIELDING HIGH-SPEED OPERATION THEREOF Filled Jan. 13, 1945 I INVENTOR "Earl chm/QM BY W1 l ATTQ gvs 7 Sept. 21, 1948.

HYDRAULIC PRESS SYSTEM WITH CONTROL MEANS YIELDING HIGH-SPEED OPERATION THEREOF Filed Jan. 13, 1943 3 Sheets-Shoot 3 48-. F 75 fyi I 0 F5 6 53 If I.

i: i :i'? 40 I 66 I '1: 66 ll H 26 I l 6? q ATTORNEY CANNON 2,449,639" 4 Patented Sept. 21, 1948 HYDRAULIC PRESS SYSTEM WITH CON-.

TROL MEANS YIELDING HIGH-SPEED OP- ERATION THEREOF Earl Cannon, Rockville Centre, N. Y., assignor to E. W. Bliss Company, Brooklyn, N. Y., a corporation of Delaware Application January 13, 1943, Serial No. 472,184

r 6 Claims. (01. 60-52) This invention relates to improvements in hydraulic press systems and more particularly relates to systems including hydraulic presses which, if desired, may be operated satisfactorily at speeds favorably comparable to the attainable speeds of mechanical presses of corresponding sizes. Such hydraulic presses are referred to herein as high speed presses.

One of the difiiculties heretofore encountered in providing high speed hydraulic presses has arisen from the fact that the reversal of the stroke of the press in both directions has ordinarily been accomplished by the use of a distributing valve operating mechanism actuated either by a cam, cooperating with a lever or switch arrangement, or by a pressure reversing arrangement, either of which functioned only upon the press ram substantially reaching the end of each stroke. This dependency of the reversing means upon the press ram reaching the end of its stroke, together with the unavoidable time factor involved in the operation of the said reversing means andin the resulting operation of the said distributing valve, caused a material lag in the reversal of the press stroke and a consequent limitation upon the operating speed of prior press systems. Even'in well-designed electrically controlled installations, the mentioned lag entailed a time loss which so reduced the at- The principal objects and broader aspects of the invention An important object of the present invention is the provision of an improved high-speed hydraulic press system, whereby to make the wellknown unique advantages of hydraulic presses available on work requiring high-speed press operation.

Another important object of this invention is the provision of means assuring that, when the press is started, its first stroke will be a complete rather than a partial stroke.

Another important object is the provision of means whereby, when the press is stopped, the ram thereof is always brought to rest at its uppermost or open position.

I Still another object is the provision of means for conveniently adapting the system either to operation wherein the reciprocation of the press ram continues uninterruptedly until stopped by tinuous operation), orto operation wherein the ram pursues only a single advance stroke followed by a single return stroke (hereinafter referred to as cyclic operation).

The foregoing and other objects, which will be apparent from a consideration of the following specification and the accompanying drawings, are accomplished, according to the present invention, by providing a liquid distributing valve which is continuously operated by a motor which functions independently of the ram of the press, and by providing other features hereinafter described.

According to a preferred form of the invention, the said distributing valve is in the form of a reciprocating slide valve in which a piston is reciprocated continuously through a lever having a fulcrum variable between one point which and in consequence the said piston may continue to reciprocate, the liquid distributing valve, instead of directing liquid to several chambers in sequence to cause the press to operate, functions to direct liquid only into one press chamber, causing the press to be opened and held open (hereinafter referred to as idling reciprocation").

The invention also includes means whereby the distributing valve is so operated that the first, as well as succeeding press strokes, are complete strokes, and also means whereby either continuous or cyclic operation may be derived in the operation of the press.

The illustrated embodiment of the invention For the purpose of illustrating the present invention and its mannerof operation and without any consequent limitation of the scope of the invention, a preferred embodiment thereof is illustrated in the accompanying drawings, in which:

Figure 1 is a diagram of a preferred embodiment of the invention;

Fig. 2 is a graph illustrating the movement of a distributing valve piston throughout a cycle of operation; also the eflfect of such movement in controlling the distribution of liquid to the the operator (hereinafter referred to as "conseveral hydraulic chambers of the press and a liquid supply tank, and the consequent effect upon the operation of the ram of the press;

Figs. 3, 4 and 5 are diagrams of a distributing valve. shown in Fig. 1, and certain parts of its operating gear, illustrating the range of operating reciprocation of a valve element in said valve;

Figs. 6, 7 and 8 are diagrams of the same general character as Figs. 3, 4 and 5, illustrating, however, the range of idling reciprocation of the mentioned valve element;

Fig. 9 is a cross-sectional view of changeable reduction gearing, the section being on the line 9-9 of Fig. 1; and V Fig. 10 is a cross-sectional view'of an idler gear 1 and its mounting, the section being on the line lll-lll of Fi 9.

Referring to Fig. 1 and observing that in said figure no attempt has been made to indicate the proportions of the various component parts of the system relatively to one another, a hydraulic press I! of a type ordinarily used for relatively light work, comprises a slide l2suitably guided valve 34 which is preferably located within the tank 23. At points near the end 'of the bore 29 for reciprocation within Jaws constituting a crown l3 and a bed [4. Upon or within the crown I3 is a cylinder l5, and within a vertical bore therein a ram I6 is accurately fitted for reciprocation. The

ram I 3, preferably is formed integrally with an extension of reduced diameter, which extends downwardly through a portion of the crown i3 and through a suitable packing assembly 88 to the exterior of said crown. The slide I2 is fixed upon the lower end of the extension ll, and, hence, the said slide reciprocates with the ram IS.

The area above the ram it within the bore of the cylinder I i constitutes a hydraulic chamber ID, the pressure in which coacts with the ram to force the latter downwardly on what may be termed its advance stroke and said chamber I9 is hereinafter referred to as the advance chamber." The area below the ram l8 and extending around the extension ll within the mentioned bore of the cylinder l5 constitutes-a hydraulic chamber 23, the pressure in which coacts with the ram to force the-latter upwardly on what may be termed its return stroke, and said chamber 20 is hereinafter referred to as the "return chamher."

A port 15a. is provided in the cylinder ii at a point substantially coincident with the lower end of the ram it when the latter is at the top of its stroke. An annular groove Nib may be provided within the cylinder I5 coinciding with the mentioned port. It should be observed that the length of the ram in relation to its stroke is such that the port l5a is uncovered only when the ram 1 is substantially in its uppermost position.

The liquid circulating system comprises a pump 2|, preferably having means which may include an adjusting wheel 22 for varying the rate of delivery of ,liquid by the pump to the press. The pump may be driven by a motor 23 to the shaft of which the pumping mechanism of the pump is suitably connected by a coupling 24. In operation the pump 2| continuously draws liquid through a pipe 25 from a tank 26 which conven-' iently may be located upon the crown 13 of the press and may extend completely about the cylinder I5.

The pump 2| discharges liquid through a pipe 21 and a port 28 into a longitudinal bore 23, at

an intermediate point thereof, within a distributing valve 3i). The said bore is connected at other intermediate points through a port 3| and a pipe 32 to the return chamber 20 and through a port 33 and a pipe 34 to the advance chamber IS, the

the latter is connected through ports 36 and 31 and pipes 38 and 39 t0 the tank 26, the latter pipe preferably being connected to said tank at an upper part thereof. For convenience in understanding the operation of the valve the several mentioned ports thereof will be referred to hereinafter as follows: the port 28 as the pump port, the port M as the return port, the port 33 as the "advance port," and the ports 36 and 31 as the "exhaust ports.

The course of movement of liquid through the valve 30 is controlled by a piston 40 which is accurately fitted to slide within the bore 29 and is preferably provided with a lower extension 4! and an upper extension 42 which extend through suitable packing assemblies 43. 44 to the exterior of the valve.

The piston 40 may be moved continuously in a reciprocating movement by a suitable motor pro-. vided solely for that purpose, or, as shown in Fig. 1, by the motor 23, which drives the pump 2!. The shaft of said motor, through easily changeable reduction gearing 45, drives a shaft 46 to which is keyed, or otherwise constrained to turn therewith, a-crank wheel 41, and the crank pin 48 of said wheel is pivotally linked by a pitrnan 49 to one end of a rocking lever 50 which ispivotally connected at an intermediate point thereof to one of the piston extensions, the said connection being to the upper extension 42 in the illustrated embodiment. The other end of the rocking lever 50 serves as a fulcrum whicl is rendered variable by pivotally connecting the latter end of the said lever through a link 5i to an end of the core 52 of a solenoid 53 mounted upon a platform 54 of a bracket 55 which may be fixed upon the casing of the valve 30.

A form of the mentioned changeable reduction gearing is illustrated in Figs. 1 9 and 10. In this structure the rotation of the rotor of the motor 23 is transmitted, through suitable transmission gears (not shown) in the transmission gear box 23a to a shaft 2%, which for present purposes may be considered as a drive shaft. The changeable reduction gearing 45, by means of which the rotation of the drive shaft 23b is transmitted to shaft 46, comprises a changeable gear 45a keyed to the 'drive shaft 231), a gear 45b keyed to the shaft 46, the end of which is carried in a suitable bearing 46a, and a changeable idler gear 450 the position of which is variable with respect to both gears 45a and 45b.

The gear 45a may be retained upon the shaft 23b by a suitable nut and lock-nut arrangement so that a larger or smaller gear 450 may easily be substituted as desired. The idler gear 450, or a substituted idler gear, may easily be rep0sitioned to properly coact with the gear 45b and a substituted gear 45a, because ofthe idler gear being mounted upon a substantially triangular plate 230 which is adapted to pivot about the drive shaft 23?). The said idler gear 450, as best seen in Fig. 10, may turn freely upon a bushing 23d, somewhat longer than the width of the hub of said gear, the bushing being secured upon the said plate by a headed bolt 23e and locking nuts 23;. The said bolt is disposed within a slot 239 in said plate and the said bushing and bolt assembly may easily be loosened and moved along the slot 23g to permit adjustment of the position of the idler gear relatively to the gear 45a. The described mountable cover did.

In the drawing, the parts of the solenoid 53 are shown in solid lines in the relative positions they assume when the latter is energized. When the solenoid is deenergized, the fulcrum end or the lever 50 and the core 52 are pushed upwardly,

as indicated in broken lines, by a compression spring 56 which may be enclosed withintelescoping tubular members 51, 58. These tubular members may be pivotally connected to the platform 54 and to a point on the lever 50 between the latters fulcrum end and the point on said lever where the piston extension is connected. The upward movement of said core and of the fulcrum end of the lever is limited by any suitable '-means, wh-ich, in the drawing, are indicated as comprising an enlarged lower end 59 of the core 52 which may be engaged and be arrested in its upward movement by the under side of the platform 54.

The piston 40 is provided with piston heads 60, El and 62- and between said heads with neckportions '63 and 64. The said piston heads have lateral passages 65, 66 and 61, extending completely through said heads and a longitudinal passage 68 extends interiorly of the piston 40 and afiords communication betwcenthe several mentioned lateral passages. The mentioned passages are adapted, at parts of the stroke of the piston, to pass pumped liquid from the pump port 28 to either or both of exhaust ports 36, 31. The said piston heads and neck portions are preferably of the size and disposition relatively to the several ports and other parts oi. the valve 30, substantially as indicated in the drawing, the said proportions being such as to yield the operation hereinafter described. It will be understood, of course, that, as a matter of design,

changes may be made in the disposition of-the mentioned ports, and corresponding changes may be made in the disposition. of the piston heads, but the design indicated in the drawing is well suited to the purposes of the present "invention.

Continuous operation .of the press system -In order to understand the operation of the press system, it will be helpful at first to assume that, when the solenoid 53 is in a de-energized state and the fulcrum end of the lever 50 is in raised position, as indicated in broken lines in the drawing, the operation of the motor 23, although causing the piston 40 to reciprocate, nevertheless will not operate the press except to hold the ram HS and the slide l2 in their uppermost positions, in which it may be said that the press is open. Therefore, in considering the operation of the press system, we may first assume that the solenoid 53 is in its mentioned deenergized condition. The motor 23 is then set in operation by the closing of a suitable switch (not shown in the drawing), whereupon idling reciprocation of the piston 40 will commence. Thereupon, in order to operate the press, an electric circuit through the solenoid 53 may .be closed by any suitable means, thereby energizing said solenoid and moving the core 52 or the latter and the tulcrum'end o! the lever 50 tothe positions thereof indicated in full lines in Fig. 1

(hereinafter referred to as their operating positions) It may be assumed for present purposes that the energizing of said solenoid takes place at the moment when the crank pin of the crank wheel 41, in its .counterclockwisemovement indicated byarrows in the drawing, reaches the point in its travel indicated as 0. By referring to the graph, Fig. 2, it is convenient to observe the movement of the -valve piston 40,

the distribution of liquid by the distributing valve 30, and also the movement of the ram it throughout a complete cycle corresponding to the turning of the crank wheel 41 through 360'. In the graph, Fig. 2, certain successive positions of the piston 40 of the valve 30, during its operating reciprocation, are indicated at vertical coordinates a-l in substantial relation to various points in the movement of the crank wheel 41 throughout its cycle indicated by vertical coordinates with suitable degree markings. Broken horizontal lines in said graph indicate the positions of the several ports of the valve 30, the range of movement of the ram l6, and also the parts of the press to which liquid is said graph the liquid being pumped is represented by a relatively broad band.

At the beginning of the cycle, as shown by the graph, the piston 40 is moving downwardly and is at position a; the entire volume of pumped liquid is passing from the pump port 28 of the valve, through the passages 56, 6:8,

and 81 to the exhaust ports of said valve, and

- start moving downwardly.

-Upon piston 40 reaching b position, passage 66 is closed ofi from pump port 28, whereupon the entire volume of pumped liquid passes into the advance chamber, and the ram then pursues a regular or uniform descent which may continue until the piston in its upward stroke' when the passage 66 commences'to reopen into communication with the pump port 28 to carry a portion of the pumped liquid to the tank 25 while a portion of the liquid still passes to the advance chamber l9. Thus, during the movement of the piston from position d to position e, the ram is decelerating somewhat until at position e the pump port 28 is completely closed oil from the advance and return ports. I

This completes isolation of the pump port from the advance and return ports continues while the piston 40 passes from position e to position 9 during which period the ram l6 remains stationary or dwells at the bottom of its stroke. When the piston reaches position 9, the head 5| commences to uncover the pump port 28 to open up communication between'said port and the return port 3| while head 6i) commences to open up communication between exhaust port 38 and 40 reaches position (I causing the ram Hi to rise at a substantially uniform speed.

Assuming that the ratio of the effective pressure receiving areas at the top and bottom of the ram I6 is as two is to one, the mentioned upward movement of the ram is twice as rapid as the downward movement thereof. reaches its uppermost position approximately at the time the crank wheel 41 completes 250 of its cycle. From this point in said cycle until about the time the wheel 41 reaches 315 in its cycle,

liquid continues to be pumped into the returnchamber 20 and the excess liquid passes therefrom through port |a in the cylinder I5, into the tank 26. The pressure incident to the pumping of such excess liquidinto said chamber serves to holdup the ram and thus open said port lia sufilcintly to enable the latter to pass such excess liquid into the tank.

At about the time the crank wheel 41 completes 315 of its cycle, the piston head 6|, during the movement of the piston 48 from position 1 to position It, covers pump port 28 and closes ofi the latter from communication with the return port 3|, thus'ending the pumping or liquid to return chamber 28. Upon termination of the pumping of liquid to the return chamber, at position k of the piston 40, the ram is descends slightly until it completely closes port l5a after which the liquid trapped in return chamber 28 holds the ram slightly below itsuppermost position until the cycle is completed and the various moving parts of the press system are in position to commence the next cycle.

Thebroken line indication of ram movement in the graph, shows a possible limitation of the downward movement of the ram, caused, for example, by a substantially thick blank or mass being pressed. If the output 0! the pump 2| and the speed of the crank wheel 41 and other factors governing the stroke of the ram were. such as to yield the full stroke indicated in solid lines in the graph, and'such a thick blank or mass were being pressed, the relief valve 85 would blow ofi during the period from :c to 11 indicated on the ram travel line in the graph.

In practice the said blow off preferably is kept at a minimum by so correlating the factors controlling the limits of the press stroke that when the piston 40 reaches its position e the volume 0! liquid pumped into advance chamber I8 is only slightly more than'enough to yieldthe desired length of the advance stroke of the ram IS. The adjustment in this respect may be accomplished by adjusting the pump 2| whereby to reduce the output thereof, or by changing the gears in the reduction gearing 45 to increase the speed oi the crank wheel 41 relatively to the motor 28. It will be understood also that the speed of the press may be varied simply by varying the speed 0! the motor 23.

Stopping the press in open position automatic. When the operation of the press is Hence, the ram to be stopped, it is, of course, desirable for the press slide l2 to come to rest in its uppermost or open position. To accomplish this, the electric circuit theretofore maintained in the solenoid 88 is opened, thereby de-energizing the said solenoid and permitting the solenoid core 82 and the i111- crum end of the lever -58 to be moved to their uppermost or idling positions, as indicated in broken lines in Fig. 1, in response to the compression of the spring 58. By thus raising the fulcrum point of the lever 50, the range of reciprocation of the valve piston 48 is raised so that although the motor 23 continues to operate without interruption, and the piston 48 continues to reciprocate, the reciprocation oi the piston head 6| of the latter is confined to the portion of the bore 28 between the pump port 28. and the advance port 88 so that the entire volume of liquid pumped into the valve 88 is directed uninterruptedly to the return port 8| whence it is carried by pipe 82 into return chamber 20 whereby to raise and hold up the ram l8,

The diilerences derived in operation of the valve 30 by changing the fulcrum point of the lever 50 may easily be understood by comparing Figs. 3, 4 and 5, which, respectively, show the positions 0! the piston 48 relatively to the several ports of the said valve when the crank pin 48 is at the top, middle and bottom oi its stroke while the fulcrum end of the lever is in its operating position, with Figs. '6, 7 and 8, which, respectively,-show the positions of the said piston when the crank pin is at the same points in its stroke while the fulcrum end of the lever is in its idling position.

The operating range of reciprocation oi the piston 40, illustrated in Figs. .3-6, is such that liquid from the pump 2l'ls directed from the pump port 28 alternately to the advance port 88 (thence to advance chamber l8) and to the return port 8! (thenceto return chamber 28), while an inverse alternation takes place in the exhaustion of liquid from the return port 8! (from return chamber 28) and the advance port 88 (from advance chamber l8), whereby to reciprocate the ram iii. In the mid-position of the operating range of reciprocation (Fig; 4), the entire output of the pump 2| is by-passed from pump port 28, through the interior passages 88,

'88, 85 and 61 of the valve element, to exhaust ports as and s1, and thence .to the tank as. This by-passing of liquid, occurring in both the downstroke and the upstroke of the crank pin 48 yields the dwell of the ram 18 at the top and bottom g! the latters stroke, as shown in the graph, Fig.

The idling range of reciprocationof the piston 48, illustrated in Figs. 6-8, is such that, in

- whereby to hold the ram and press slide in their uppermost or open positions.

The liquid continuously being pumped into the return chamber during idling reciprocation oi the piston 48 holdsup the ram sufficiently to at least partly open the port Ilia through which the pumped liquid continues to pass to the tank 28 until the press is again operated or until the motor 28 is stopped. Ii the motor 28 is stopped whenthe press is open, the ram It moves downwardly until the lower end thereof closes the port Ia after which the ram is held In position, in-

dicated}by the broken line in 'Fig. 1, by the liquid confined within the return chamber 20,

Desirable objectives in the control of the press The foregoing description explains the manner in which continuous operation of the press is established. maintained and terminated, and. insofar as control means were concerned in said understood from a description of the operation thereof. I

Control of continuous operation Assuming that the operator desires to establish continuous operation of the press, and that the solenoid 53 is in de-energized condition, so

that the piston 40 is undergoing idling reciprocathe art for accomplishing such operation of the said motor and solenoid. In actual practice, however, it is often desired that instead of operating the press continuously, it should be operated only through a single cycle at a time, which operation is herein referred to as "cyclic operation. Such operation involves merely the closing and opening of the press, bringing it to rest at the top of the stroke of the press slide, so that the time during which the press is open for reloading 'of a blank or blanks is entirely within the control of the operator: 1 Within the present invention an electric control system may be provided to permit either continuous or cyclic operation of the press as desired. Fig. 1 includes a diagram of such a control system. Before describing the electric control system, it is wellto note the importance of having the energizing of the solenoid 53 occur during'the latter part of a cycle of the crank wheel 41 so 'that, in either continuous or cyclic operation of the press, the first advance stroke or the only advance stroke'will be a full-length stroke derived from the pumping of a full charge of liquid into the advance chamber rather than a partial stroke which would be derived if the solenoid were to be energized at any time during the movement of the crank wheel between 0 and about 135 in its cycle.

The control system disclosed and described herein is adapted to assure that even though a starting switch is operated during the mentioned early part of said cycle, the solenoid, nevertheless, is not energized until at, or slightly before, the end of said cycle so that the resulting advance stroke of the ram I6 will be a full-length stroke.

The means for controlling the operation of the The electric control system includes a normally open limit switch IOI which is so positioned adjacent the crank wheel 41 that, when the crank pin 48 reaches the position indicated as zero degrees, the said switch is engaged and closed by a cam I02 which is slotted and adjustably mounted upon the crank wheel 41 by .a set screw or other suitable means which will permit the said cam to be adjusted circumferentially of the crank wheel within certain limits. The electric system tion, he first closes selection switch I04. Then he momentarily presses starting switch I05, thus establishing a circuit from positive lead I00 through said starting switch, thence by wire I01 through relay coil I08, wire I09, selection switch I04, wire H0, and press-button stop switch III to negative lead 2. The closing of said circuit causes relay contactor I08a to close a holding circuit through wires H3 and bridging the starting switch I05 so that, when .the latter switch is released and opened, the said If, at the moment the starting switch I05 is closed and, in consequence, the relay contactor W8!) is closed, the crank wheel 41 is in a position in which the cam I02 is not in operating engagement with the limitswitch If, there is no immediate closing of the last-mentioned circuit, but suchclosing occurs at the instant the cam I02 engages and closes the said limit switch. Upon the closing of said circuit and the consequent energizing of relay coil H8, relay contactor Ba closes a holding circuit through wires I20, I2I

and I I1 bridging both the limit switch IN and relay contactor I08b in this way maintaining the circuit through relay coil II8 even after the cam I02 disengages and opens the limit switch IOI with the continued movement of the crank wheel 41.

As a result of the establishment and main tenance of the mentioned circuit through relay fcoilII8, relay contactors H81: and 80 close a circuit through the coil of the solenoid 53, extending between leads I06 and H2 and including, in addition to said contactors and solenoid, wires I23, I24, I25 and I26. The establishment and maintenance .of the mentioned circuit through the coil of solenoid 53 energizes the latter and causes the solenoid core 52 and the fulcrum end of the lever 50 to move downwardly from their idling positions, as indicated in broken lines in Fig. 1, to their operating positions, indicated in full lines, thus causing the valve 30 to distribute pumped liquid and operate the press in the manner indicated in the graph, Fig. 2.

The press operates continuously during the maintenance of the said circuits through the coils of the several mentioned relays and the solenoid. To stop such operation. the stop switch III is opened to bring the press to rest. The opening of said stop switch breaks the circuits through both relay coils I08 and H8, thus moving all mentioned relay contactors to their open positions and de-energizing solenoid 53 to permit the fulcrum end of the lever 50 to be moved to its idling position by the compression spring 50. As

11 already explained, the shifting of the mentioned fulcrum point to its idling position causesv the press to stop and the ram. I6 to come to rest at its uppe' st position.

Control of cyclic operation Assuming that the operator desires to employ noid 53 is in'de-energized condition, so that the piston 40 is undergoing idling reciprocation. he first makes certain that selection switch I04 is open; Then he momentarily presses starting switch I05, thus establishing a circuit from lead I06 through said starting switch, thence by wire I01 through relay coil I03, wire I09, wire I21, normally closed limit switch I03; lwire I28, wire H0 and press-button stop switch III to lead 2. This circuit constitutes the only difference The clo s'ing'of said circuit through relay coil I08 functi ens'in the manner already described- (with reference to continuous operation) to cause circuits to be closed and maintained through relays H3 and solenoid 53 to start operation of the press. However, although limit switch I03 is entirely ineffective in continuous operation of the press because of being connected in parallel with selection switch I04, which is closed during such continuous operation, said limit switch I03, when the switch I04 is open for cyclic press operation, is effectively in series with stop switch III. Thus, limit switch I03 is adapted to function as a stop switch. In the same manner as the opening of stop switch III functions to bring the press ram to rest at the. top of its stroke under continuous operation, the limit switch I03, upon being engaged and opened by the cam I02 upon the completion of approximately 180 of the crank wheel cycle, functions to break the circuits through the several relays, including their respective holding circuits, and as a result breaks the solenoid circuit whereby to bring the ram I6 to rest in its uppermost position in the manner already described.

that the said valve is positively operated or driven independently of the movement of the ram or of the pressure present in any ram actuating chamber, in contrast to prior systems wherein the operation of a distributing valve was substantially controlled by the movement. of the ram or I by the pressure in one or the other of hydraulic cyclic operation of the press and that the solechambers causing such ram= movements or by other means directly associated with the ram or therewith is indicated by referring to the said The closing of the mentioned circuit through limit switch I03. will take place at the instant the starting button is pressed only if at that instant the cam I02 is. not in operative or opening engagement with the normally closed switch I03.-

However, if at the instant the starting button is pressed, the cam I02 is in engagement with the limit switch I03 and is holding the latter open, that condition would obtain only momentarily inasmuch as the normal duration of the manual holding of the starting switch I05 in its closed position would be greater than the time during which the cam I02 holds the switch I03 open.

It should be observed that, although an attempt has' been made, in the foregoing description, to show quite accurately the relationship of the movement of the ram to thereciprocation of the piston of the distributing valve, a difference, not reflected in this description, may occur, in practice, in the relative movements of said ram and piston as a result of the inertia of the ram and of the liquid in the system and possibly as a result of other factors. This description,

distribution means including a distributing valve.

valve as operated independently of control by the movement (or reciprocation) of said reciprocatingmember (or ram)" or by other words of simi lar import.

If it is desired, in practice, to change the char acteristics of the graph line indicating the movement of the ram, as, for example, to shorten either or both periods of dwellat the extremities of the ram stroke, a'suitable cam arrangement or other suitable means could be used, within the present invention, instead of the crank wheel, to reciprocate the valve piston. Also, it should be obvious that, if desired, the control apparatus could be so arranged that the solenoid would be de-energized to start the operation 'of the press and energized to stop the press operation.

It is apparent that the press system described herein afiords substantial flexibility of adjustment of the length and speed of stroke of the press ram and that various changes may be effected in adjustment, design, structure or operation without, however, departing from thespirit of the invention.

What I claim is:

1. In a hydraulic, material-forming press system, the combination of a distributing valve hav- ,ing a movable valve element shiftable from either to the other of an operating range of movement adapted to control delivery of liquid to a hydraulic press so as to continuously operate the latter, and anidling range of movement adapted to control delivery of liquid to such a press so as to cause the press to open and remain open, means 'for' continuously actuating said valve element, and means for shifting the latter from either to the other of the two said ranges of movement thereof, the said actuating means comprising a valve gear, and a motor connected through said valve gear to said valve for operating the latter, the said shiftingv means comprising an oscillating lever, connected to said valve element and constituting a part of said valve gear, and means for varying the fulcrum-point of said lever, the latter means comprising a solenoid having a core to which the lever is pivotally connected at its fulcrum-point.

2. A hydraulicpress system comprising a press having a reciprocable ram adapted to impose force upon material to form the latter, a continuous-delivery pressure-liquid supply, liquid having a reciprocable valve element for controlling thedistribution of liquid, from saidsupply, .with respect to said ram to reciprocate the latter, a continuously-operable fixed-stroke eccentric device and motion-transmitting means in- .cluding a lever coacting with said device and said valve element for reciprocating the latter independently of said ram, and control means, independentoi said ram, for changing the motiontransmitting means from either to the other of an operating condition in-which. the said ram reciprocates, and an idling condition in which 13 the said ram is at rest, the said control means comprising a shiftable fulcrum-point support for said lever, shifting means, including electromagnetic means, for shifting said support from either to the other of a first position characteristic of such operating condition of said motiontransmitting means, and a second position characteristic of such idling condition of said motiontransmitting means, an electric circuit for controlling the operation of said electromagnetic means, starting-switch means, associated with said circuit, which are manually controllable to cause the 'said shifting means to shift and hold the saidlever in its mentioned first position, and stopping-switch means, associated with said cirsuit, which are automatically operable in timed relation to said eccentric device to cause the said shifting means to shift and. hold the said lever in its mentioned second position.

3. A hydraulic press and controls therefor, comprising a reciprocable ram, a reciprocable valve for controlling the distribution of liquid with respect to said ram to reciprocate the latter, driving means, including a lever coacting with said valve element, for reciprocating the latter independently of said ram, and control means, independent of said rain, for changing the said lever from either to the other of an operating condition, in which the said ram is caused to reciprocate, and an idling condition in which the said ram is at rest, the said control means comprising a shift- I .of such idling condition of the said lever, an

electric system for controlling the operation of said electrically-actuated means, starting-switch means, in said system, which are at least partially manually controllable to cause the said shifting I means to shift the said lever to and hold it in its mentioned first position to establish reciprocation of the said ram, and stopping-switch means, in said system, which are automatically operable in timed relation to said driving means to cause the said shifting means to shift thesaid lever to and hold it in its mentioned second position to discontinuereciprocation of the ram.

4. A hydraulic press and controls therefor, according to claim 3, the said starting-switch means including a starting switch, manually. operable to effect incomplete conditioning of the electric system for causing reciprocation of the ram, and a switch, automatically operable in timed relation to said driving means, to complete the conditioning of the electric system for causing reciprocation of the ram.

5. A hydraulic press and controls therefor. comprising a reciprocable ram, a reciprocable valve for controlling the distribution of liquid with respect to said ram to reciprocate the latter, driving means, including a lever eoacting with said valve element, for reciprocating the latter independently of said ram, and control means, independent of said ram, for changing the said lever from either to the other of an operatingcondition,

trically-actuated means, for shifting said support between a first position characteristic of such operating condition of the said lever and a second position characteristic of such idling condition of the said lever, further characterized in including an electric system for controlling the operation of said electrically actuated means, starting switch means, in said system, which are at least partially manually controllable to cause the said shifting means to shift the said lever to and hold it in its mentioned first position to establish reciprocation of the said ram and manually operable stopping-switch means, in said system, adapted to cause the said shifting means to shift the said lever to and hold it in its mentioned second position to discontinue reciprocation of the ram.

6. A hydraulic press and controls therefor, comprising a reciprocable ram, a reciprocable valve for controlling the distribution of liquid with respect to said ram to reciprocate the latter, driving means, including'a lever coacting with said valve element, for reciprocating the latter independently of said ram, and control means, independent of said ram, for changing the said lever from either to the other of an operating condition, in which the said ram is caused to. reciprocate, and an idling condition in which the said ram is at rest, the said control means comprising a shiftable fulcrum-point support for said lever, shifting means, including electrically-actuated means, forv shifting said support between a first position characteristic of such operatingcondb tion of the said'lever and a second position characteristic of such idling condition of the said lever, an electric system for controlling the operation of said electrically-actuated means, manually con.-

REFERENCES crrEn The following references are of record in the file of this patent:

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